What exactly does update.zip consist of? ZTE MErit boot-looped at Android System Recovery

What exactly does update.zip consist of? My merit is boot looped at "Android System Recovery". (ASR)

It is a ZTE Merit 990 on Straight Talk. I believe I flashed a wrong ROM. When the phone boots up, it displays the "Rethink Possible" logo for about 10 seconds(had one.three flashed originally) and then it goes straight to ASR.

I've attempted to create an Update.zip from different roms and stuff floating around on this forum and elsewhere, but the end result for all of them is "installation aborted".

I have another ZTE Merit on the way just in case my soft-bricked Merit happens to be permanently bricked. But I intend to at the least make a nandroid back-up of the phone before any of my info is put onto the phone, and make it available to all.

Also wondering if somebody can guide me to documentation that will explain how to create a ROM image, to also make the original ROM available to others. I know there are others who are also looking for the original ROM for the Straight Talk ZTE Merit 990.

Lastly, rescuing my phone absolutely has to be done through Update.zip because It is unrecognizable to USB at the moment which rules out using ADB or anything like it. I've done much reading and tried everything. Please don't waste my time or yours explaining how to hold buttons to boot up or wipe user settings. Been there, done that. The CWM menu is also gone. Only ASR exists now. I'm looking specifically for info on "update.zip" that will restore an original ROM. If I have to provide that ROM after I get the new phone then fine, but I don't know how to retrieve or create the ROM image at this point, outside of a nandroid back-up.

Since making this post, I've learned a little more. None of the update.zip files I made were signed. Still don't know how to sign, although I suspect at least one of the problems may be from using an unsigned update.zip.

I did a "system pull" before doing anything else to the NEW phone. (other than rooting)
I also have a nandroid backup of the original set-up, should anybody need or want it.

Yes, I had CWM properly installed and it worked great...but like I said in the other thread, I replaced the CWM 'Recovery.img' with another ROM's 'Recovery.img'. Neither the 'Recovery.img' nor the ROM 'took'. So now the phone only boots up to ASR regardless of what you do. It seems to be actually checking and attempting to process whatever update.zip is loaded onto the SDcard.....but it always aborts.

If I could somehow "update" the recovery to CWM then the problem would be solved. I might have to head over to XDA with it and see if somebody might be interested in taking a look into it.

Speaking of XDA, here's a funny XDA Youtube video called "You are a noob."

EDIT: OK....I didn't realize how this looked. The noob vid was NOT directed at anybody here.
When I mentioned XDA it reminded me of the video I had just seen, which had cracked me up.

I have one that I created that I just repaired my longtime-bricked Merit with, along with napalm6283's "Update.zip". I'm not sure how and where to share it. If somebody wants to point me to a decent file sharing site that won't take the files down for whatever reason, please advise.